There is known a method of cold welding components formed as cylindrical bodies of rotation, particularly tubes, consisting in pressing the components one into another by applying an axial stress to at least one of such components.
The process is carried into effect as follows.
The end faces of the tubes to be joined are first cleaned, followed by preparation for overlap joining of the same, i.e. one of the tube ends is expanded such that the inner diameter of the tube is made slightly smaller than the outer diameter of the second tube. An axial stress is applied to press the end of one of the tubes into the other tube, followed by peeling any oxide film off the tube ends. The components are then welded together by applying a radial stress as the tube ends are swaged on a mandrel.
The known process is largely unsuitable for use in welding tubes of a material less plastic than aluminum, which requires a much higher stress to secure a welded joint, the resulting joints being largely destroyed by residual strain as the joint-forming stresses are released. The material is subject to heavy cracking at the time of its plastic working. The method is not adapted for joining tubing of a soft and hard metal, the radial compression of the ends of such tubes in the absence of complimentary operations leaving the harder metal either little strained or not at all so that a strong joint is not formed. The carrying of the method into effect further involves the use of specialized welding equipment.